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BillyHvac, Journeyman HVAC Tech
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i have a generalaire B2015-S85 solenoid in series with a dna

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i have a generalaire B2015-S85 solenoid in series with a dna group humidistat (#884021B). I confirmed I have water supplied to the solenoid valve. Since the humidifier isn't working, i.e. no water to the filter media, how do i check the valve and the control to see determine whether they are working or not?
Do you have meter? Or would you like to troubleshoot by other means
Customer: replied 7 years ago.

I do have a meter



First w need to start at power source. Some furnaces have humidifier terminals that only hot when the gas valve is energized. What furnace do you have? Or do you know if your source is hot and when?

Customer: replied 7 years ago.
the gas furnace is a carrier weathermaker 9300TS. i am measuring about 14 VAC across the leads that connect to the humidistat.


That is a 24 volt terminal from circuit board.


You will need to go to point of power origination. Remove wires from HUM terminalsand measure voltage there.

Customer: replied 7 years ago.
think i found the problem . . . one side of the circuit was not connected to the PCB HUM terminal, so the circuit did not appear to be closed . . . your thoughts?

It is either miswired or came apart. Check HUM to terminal C for 24 volts during the furnace cycle. Once again HUM is 24v hot only while the gas valve is energized.


From hum the 24v goes to one side of humidistat, out the side of humidistat to one side humidifier, out humidifier and back to common.

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Customer: replied 7 years ago.

once i connected the lead to the terminal on the circuit board, the solenoid opened and began working during a heating cycle. thanks.


Excellent. I am glad it worked for you.


I would be more proud if I fixed it but you beat you me to it...well done!